A 0.100" contact spacing within a single row is considered the present practical limit for standard spacing in existing miniature electrical connectors.
Recently designers have been increasing number of functions per electronic package; this, together with space and speed requirements of many applications, has forced into existence connectors with higher density contact spacing, such as 0.050" within a single row.
However, severe physical constraints of such spacing have made it difficult to produce reliable and economic connectors.
The object of this invention is to achieve the contact reliability, mechanical integrity, and economy of standard spacing connectors, such as 0.100", in higher density spacing connectors, such as 0.050", 0.0375", or even less, to which this invention specifically but not exclusively relates.
Two rows of contacts having mating means on 0.050" pitch within each row can be further interlaced to provide an effective edge spacing of 0.025".
This invention provides high contact density receptacle connectors for mating with blade contacts, which can be utilized for disengageably connecting substrate-mounted electronic devices to a printed wiring board.
The term "substrate" as used in this specification, broadly encompasses ceramic substrates, printed circuit boards, flexible circuits or cables or any panel member provided with electrical conductors in either wired or printed form.
The term "blade contact" encompasses square and rectangular posts and thin metal flat or formed blades.
Another object of this invention is to provide a simple and versatile resilent coupling contact means which can be mounted on an extremely small pitch and adapted to numerous applications by providing suitable extensions to the mating means.
One such extension to the blade contact is a solder or a pressfit and solderless wrap tail, and for the receptacle contact a cantilever tab terminal means for resilently receiving a module package board.
A basically planar construction of the receptacle contacts, characterized by lack of severe forming operations between the blank stage and the final stage in a progressive contact-forming die, affords an efficient stock to scrap ratio and good tolerance control since the functional dimensions are blank dimensions and only minor forming operations are required to convert the blank to a finished part.
The lack of severe forming operations such as right angle folds, permits use of highest strength contact spring materials since the strip temper does not have to be compromised by elongation requirements.
The planar construction of receptacle contacts is particularily suitable for mounting on a small pitch.
In addition, an efficient space utilization along the pitch is effected by mutually offsetting the free end noses of the cantilever mating means including the contact areas on their apexes, (called load points throughout this specification), horizontally side by side, or vertically to different levels and correspondingly profiling the surrounding insulator partitions. The offsetting of the load points of the resilent cantilever mating means also permits using a very thin metal mating blade and contact preload since the limitations associated with ordinary post receptacles having mutually opposing cantilever load points are absent.
While in the ordinary contact a minimum gap has to exist for plating and cleaning requirements and is difficult to control as a result of folds, the planar contacts with offset cantilevers afford a negative effective gap whose magnitude can be precisely controlled.
A still further object of this invention is to provide high module board retention force by permanently but replaceably driving the substrate between two rows of metal cantilever tabs extending upwardly from the receptacle means and outwardly above the insulator housing. This effects high pressure registrations on the substrate pads and permits infra-red reflow-soldering, visual inspection of registration, and on-duty contact probing.
One cantilever tab of each common pair makes electrical contact with the pad on the component side of the package substrate, the other tab providing back-up means and, if desired, serving as a jumper to the other side of the substrate.
The tails of successive contacts can be alternately rotated in the housing 180 degrees to plug into an offset hole pattern in the circuit board.
Similarly, the substrate receiving cantilever tabs can be made to project by uneven distances to further stratify the connections in order to improve registration and relax tolerancing.